1. Field of the Invention
The present invention relates to a mobile communication terminal device and server device having a security communication function.
2. Description of the Related Art
Conventionally, in a wireless communication system, a communication procedure referred to as authentication has been employed between the portable communication terminal device and communication system for confirming the validity of the person or the terminal at the other end of the line. Moreover, in order to encode signals transmitted and received between the portable communication terminal device and communication system, a communication procedure referred to as ciphering is also concurrently employed. Pursuant to these communication procedures, the mobile communication terminal device and communication system are able to mutually guarantee the validity of the opponent, and, simultaneously, the confidentiality of the transmitted and received signal is retained. This prevents an individual from trying to pass oneself as the caller or receiver in order to alter or scope data. Security of the communication and communication system is ensured thereby.
In an analog wireless communication system, it was necessary to change the analog wireless modulation method for ensuring the security described above. Thus, a circuit for changing the modulation method had to be added to or installed in the modulation and demodulation circuit of the communication system and mobile communication terminal device. As a result, the communication system cost would increase, and power consumption would increase pursuant to the additional circuit of the mobile communication terminal device, thereby causing significant decrease in portability. Further, there is an additional problem in that the communication signal quality cannot be maintained easily due to the increase in the operational process of analog signals of the added circuit.
Thereafter, in digital wireless communication, authentication and ciphering with digital signal processing have been proposed and it has became easy to ensure security. Nevertheless, when connecting a mobile communication terminal device and a communication system operating on the digital system, there is a premise of the ensurement of such security based on the aforementioned authentication and ciphering. In a wireless mobile communication method, regarding a delay in the connection of a call, it is not desirable that the design requires a long time to connect the call in comparison to a wired telephone connection from the perspective of service. Moreover, in data communication, it is also preferable that the connection delay be kept to a minimum even for interactive uses such as upon using the web browsing. Based on such demands, in the connection of a mobile communication terminal device and a communication system, the design is such that the time required from the start of connection to authentication and ciphering is kept to a minimum.
FIG. 10 is a diagram illustrating an example of the communication procedure of the authentication and ciphering conventionally employed upon connecting a mobile communication system and mobile communication terminal device. As shown in FIG. 10, after the radio bearer connection procedure is started from the stand-by mode, an authentication request is made from the communication system to the mobile communication terminal device. The mobile communication terminal device makes an authentication response to the communication system upon receiving the authentication request. Next, the communication system makes a ciphering request to the mobile communication terminal device, and the mobile communication terminal device makes a ciphering response thereto. Then, the line connection procedure is commenced, and the routine proceeds to the connected state. As described above, the design is such that the authentication and ciphering are completed with the transmission and reception of a few signals. Therefore, the user is able to immediately make communication without having to recognize the contents or situation of the communication procedure of authentication and ciphering upon receiving or making a call.